Secretary of State Hillary Clinton was hospitalized Sunday after doctors discovered a blood clot during a follow-up exam related to a concussion she suffered this month , her spokesman said .

She is expected to remain at New York Presbyterian Hospital for the next 48 hours so doctors can monitor her condition and treat her with anti-coagulants , said Philippe Reines , deputy assistant secretary of state .

`` Her doctors will continue to assess her condition , including other issues associated with her concussion , '' Reines said . `` They will determine if any further action is required . ''

Reines did not specify where the clot was discovered .

Clinton , 65 , was suffering from a stomach virus earlier this month when she fainted due to dehydration , causing the concussion .

Clinton spent the holidays with her family last week after working from home .

She was scheduled to return to work at the State Department this week after being sidelined for the past three weeks . Her illness forced her to bow out of testifying December 20 before the House Foreign Affairs Committee on the deadly attack on the U.S. Consulate in Benghazi , Libya . Deputies Thomas Nides and Bill Burns appeared in her place .

The medical setback comes as Clinton is wrapping up her busy tenure as secretary of state , during which she has logged more than 400 travel days and nearly a million miles . She plans to step down from the post if and when Sen. John Kerry -- President Barack Obama 's choice to replace her -- is confirmed by the Senate .

Read more : Hillary Clinton fast facts

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The clot was discovered in a follow-up exam related to her concussion

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Clinton is expected to remain hospitalized for at least the next 48 hours

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She was scheduled to return to work this week after recovering from the concussion